Interface Guide¶

This page provides detailed reference for XdTd's interface elements, dialogs, and operations. For the conceptual overview, see Key Concepts.

Part 1 — Case Study Operations¶

Everything in this section is accessed through the panel view and saved to the case study (.xdtd file).

The vertical toolbar on the right side of the panel window is organized into groups:

File & Export

Weight and Cost — view weight and cost summary for the panel
Save — save the case study (Ctrl+S)
Export Picture — export the current panel view to an image file

View

Reset View — reset pan/zoom to the default view
Settings — open application settings

Clipboard

Clear Clipboard — discard the clipboard contents
Cut (Ctrl+X) — cut selected component (removes from panel, stores in clipboard)
Copy (Ctrl+C) — copy selected component to clipboard
Paste (Ctrl+V) — paste from clipboard (geometry must be redefined)
Delete (Del) — delete selected component

History

Undo (Ctrl+Z) — undo the last operation. Dropdown shows up to 10 recent actions.
Redo (Ctrl+Shift+Z) — redo the last undone operation.

Mesh

Generate Mesh — create the boundary element mesh
Make Finer Mesh — regenerate with finer discretization
Delete Mesh — remove the mesh (unlocks geometry for editing)

Analysis

Run New BEM Analysis — configure parameters and run an analysis
Delete Selected Results Sets — remove result sets from the case study

Comparison

Compare Side by Side — compare result sets in separate charts
Compare Mixing Results — overlay result sets in the same chart

These comparison buttons operate within the current case study. For cross-case-study comparison, see Part 3.

Panel Geometry¶

When creating a new panel, XdTd offers a range of predefined topologies:

Topology	Description
Rectangle	Straight edges, suitable for basic stress analysis
Rounded Rectangle	Reduces stress concentrations at corners
Circle	Uniform stress distribution, no corner concentrations
Ellipse	Elongated structures or optimized weight designs
Triangle	Delta-shaped structures or corner regions
Trapezoid	Tapered structural components with parallel top and bottom edges
Regular Polygon	Multi-sided symmetric structures (pentagon, hexagon, etc.)
Slot	Structures with oblong holes or slotted connections
Semi-circular Cutout	Edge-notched or half-hole configurations for crack growth studies
Lug	Pin-loaded holes in mechanical joints
Test Specimen	Standard tensile test specimen configurations
T-shape / Cross / C-channel	Custom polygon templates opened in the geometry builder
Import	Arbitrary panel shapes from an external file

The geometry dialog shows a live preview. Adjust parameters on the left, then click Update Graphic View to refresh. Use Restore to return to the initial values.

Edge Operations¶

Operation	Description
Split > At a Point	Split an edge at a parametric position
Split > N Times	Split an edge into N equal segments
Boundary Conditions > Create	Define a new BC on this edge for the active BC set
Boundary Conditions > Change	Modify the existing BC on this edge
Boundary Conditions > Delete	Remove the BC from this edge
Force Discretization	Control how loads are discretized along the edge
Results > Displacements	View displacement results along the edge
Results > Stresses	View stress results along the edge

Vertex Operations¶

Operation	Description
Boundary Conditions > Create/Change/Delete	Manage BCs at this vertex
Edge Crack > Add	Define an edge crack starting from this vertex
Edge Crack > Change Geometry	Modify an existing edge crack
Edge Crack > Delete	Remove the edge crack

External Boundary Operations¶

Operation	Description
Browse > Geometry	View the boundary geometry summary
Properties > Change Geometry	Modify the panel shape
Properties > Change Material Properties	Set sheet material and thickness
Boundary Conditions > All Edges/Vertices	Apply BCs globally
Add > Internal Boundary	Add a hole or cutout
Add > Embedded Crack	Add an internal crack
Add > Stiffener	Add a stiffener reinforcement
Add > Patch	Add a patch reinforcement
Results	Access all result visualizations (see Part 2)

Internal Boundary Operations¶

Operation	Description
Browse > Geometry	View the boundary geometry
Properties > Change Geometry	Modify the cutout shape
Boundary Conditions > All Edges/Vertices	Apply BCs to all edges/vertices
Results > Boundary Displacements/Stresses	View boundary results

Stiffener Operations¶

Operation	Description
Browse > Geometry / Attachment	View stiffener geometry or attachment details
Properties > Change Geometry	Modify position, orientation, length
Properties > Change Material Properties	Set stiffener material
Properties > Change Cross Section	Set cross-section (area, moment of inertia)
Properties > Attachment > Fastened	Switch to riveted/bolted connection
Properties > Attachment > Bonded	Switch to adhesive connection
Boundary Conditions	Set loads at stiffener end points
Results	Stiffener stresses, attachment stress-strain, deformation, residual strength

Patch Operations¶

Operation	Description
Properties > Change Geometry	Modify patch polygon
Properties > Change Material Properties	Set patch material
Properties > Attachment > Fastened	Switch to riveted/bolted connection
Properties > Attachment > Bonded	Switch to adhesive connection
Results	Patch displacements/stresses, attachment forces/deformation

Crack Operations¶

Operation	Description
Browse > Geometry	View crack geometry
Properties > Change Geometry	Modify crack length
Results > Stress Intensity Factors	View SIF values
Results > Residual Strength	View residual strength curves
Results > Crack Growth > Cycles	View cycles to failure
Results > Crack Growth > da/dN	View crack growth rate
Results > Crack Growth > Growth Path	View crack trajectory

Material Properties Dialog¶

Set the sheet or reinforcement material properties. Properties can be loaded from the material database or entered manually.

Sheet Material Fields¶

Field	Description
Description	Database code or user-defined name
Young's Modulus (E)	Stiffness in tension/compression — used in stress and displacement calculations
Poisson's Ratio (v)	Ratio of transverse to axial strain — typically 0.25 to 0.35 for metals
Shear Modulus (G)	Stiffness in shear — related to E and v by G = E / (2(1+v))
Yield Strength (oy)	Stress at which plastic deformation begins — used in residual strength calculations
Ultimate Strength (ou)	Maximum stress before failure — critical for residual strength analysis
Ultimate Strain (eu)	Maximum strain at failure — used in strain-based failure criteria
Fracture Toughness (Kc/KIc)	Resistance to crack propagation — critical for residual strength determination
Thickness	Used for stress calculations and plane stress vs. plane strain conditions

Crack Growth Parameters¶

Field	Description
Crack Growth Formula	Crack growth law corresponding to the parameters below
Constant (C)	Multiplier in the da/dN equation — material-specific from fatigue testing
Exponent (m)	Stress intensity factor range exponent in Paris law: da/dN = C(DK)^m

Reinforcement Material Fields¶

Same fields as sheet material, with the addition that higher stiffness provides better crack bridging and load transfer, and Poisson's ratio mismatch with the base material can create interfacial stresses.

Boundary Conditions Dialog¶

Edge Boundary Conditions¶

Each edge can have boundary conditions in two directions (X/tangential and Y/normal), with values at the start and end points allowing linear variation along the edge.

Setting	Description
Application	Nodes (discrete points) or Elements (distributed along edge)
Reference Frame	Global (model X-Y axes) or Local (edge-aligned coordinates)
Type (X and Y)	None (free), Traction (applied force/stress), or Displacement (fixed/prescribed motion)
Start Value	BC value at edge start point — units depend on type
End Value	BC value at edge end point — allows linear variation

Analysis Parameters Dialog¶

These parameters are configured when running a new analysis and are saved with the result set.

Crack Growth¶

Setting	Description
Number of Increments	Number of crack growth increments to simulate
Increment Strategy	Multiple of crack tip element size, or user-defined length
Straight Crack Growth	Skip direction calculation if cracks are known to grow straight — saves computation
Same Growth Rate	Skip individual rate calculation if cracks grow at the same rate — saves computation
Stress Ratio	Stress ratio (R) for fatigue crack growth using Paris or Forman equation

Attachment Behaviour¶

Choose how attachments respond during analysis: rigid, elastic, elastic but breaking at force limit, plastic, or plastic but breaking at deformation limit.

2D Analysis Case¶

Select the analysis type (plane stress or plane strain).

Part 2 — Results Exploration¶

Every chart window includes a results toolbar on its right side. This toolbar provides tools for exporting, importing, configuring, and comparing results.

View¶

Reset View — reset the chart to its default zoom and position
Change View Parameters — open the chart configuration dialog (see below)

Export¶

Export Picture (graphical file) — save the chart as PNG, JPEG, or SVG
Export Picture (HTML) — save as an interactive HTML file
Export Data (CSV) — export the chart data to a CSV file
Export Data (SQLite) — export the chart data to a SQLite database
Save Config (.xdchart) — save the current chart configuration for later reuse

Import¶

Import Data (CSV) — overlay reference data from a CSV file onto the current chart
Load Config (.xdchart) — restore a previously saved chart configuration

Parameterization & Delta¶

Create Parameterized Picture — generate a percentage-difference chart using one trace as the reference
Create Delta Picture — generate an absolute-difference chart between two traces

Comparison (within current case study)¶

Compare Results Sets Side-by-Side — open selected result sets in a grid layout
Compare Results Sets Overlaid — overlay selected result sets in the same chart

These buttons are enabled only when two or more result sets are available.

Chart Configuration¶

The Change View Parameters button opens a configuration dialog specific to the current chart type. Common options include:

Graph scaling — adjust chart size (50–100%)
Show legend — toggle legend visibility
Show bounding box — toggle axis box
Show colorbar — toggle colorbar for contour plots
Chart title — set or hide a custom title
Axis ranges — set X, Y, and Z ranges manually

Additional data-specific parameters vary by visualization type (e.g., stage selection, component filtering).

Available Result Types¶

Sheet Results¶

Boundary Stresses / Displacements — stress and displacement along boundaries
Sheet Displacements — 2D and 3D views of the displacement field
Sheet Stresses — 2D filled contour, line contour, scatter, or line plots; 3D scatter or surface

Crack Results¶

Stress Intensity Factors (SIF) — K1, K2 values at crack tips
Residual Strength — panel load capacity as a function of crack length
Crack Growth — Cycles — crack length vs. number of fatigue cycles
Crack Growth — da/dN — crack growth rate
Crack Growth — Growth Path — spatial crack trajectory

Stiffener Results¶

Stiffener Stresses — stress distribution along the stiffener
Attachment Stress-Strain — chart, status by location, animation
Attachment Deformation — deformation at each attachment point
Attachment Forces/Stresses — force distribution at fastener/bond points
Residual Strength — stiffener contribution to residual strength

Patch Results¶

Patch Displacements / Stresses — 2D and 3D views
Attachment Forces/Stresses — 3D scatter, 2D filled contour, 2D line
Attachment Deformation — 3D scatter, 2D filled contour, 2D line

Part 3 — Results Comparison¶

XdTd provides two levels of results comparison, depending on whether you are comparing within a single case study or across multiple case studies.

Within a Case Study¶

From the panel toolbar or the results toolbar, click Compare Side by Side or Compare Mixing.

A dialog lets you select:

Which result sets to compare (two or more required)
Which component type (sheet, stiffeners, patches)
Which component numbers (specific components or all)
Which stages (specific crack growth stages or all)
Which result type and graphical output

This is useful for comparing the effect of different analysis parameters, BC sets, or mesh refinements on the same geometry.

Across Case Studies¶

From the main window menu, select Compare Results > Side by Side or Compare Results > Mixing.

The same dialog appears, but now it shows result sets from all open case studies. This lets you compare results across different structural configurations — for example, comparing a panel with 5 stiffeners against one with 7 stiffeners, or different materials.

The available component types are filtered to the intersection of what exists across the selected case studies.

Cost and Weight Comparison¶

From the main window menu, select Compare Cost and Weight > Side by Side or Compare Cost and Weight > Mixing.

This is available when two or more case studies are open and allows direct comparison of the cost and weight of different design alternatives.

Part 4 — Global Settings¶

Settings are accessed via Application > Settings from the main window menu, or the Settings button on the panel toolbar. They are saved to ~/XdTd/_settings/XdTd2d_user_settings.json and apply globally — they are not saved to individual case studies.

The settings dialog is organized into five groups:

Analysis Parameters¶

Output Control¶

Setting	Description
Formatted Output	Format for supplementary output files: None, Markdown, CSV, or Both

Stress Intensity Factors¶

Setting	Description
SIF Calculation Method	J-Integral or Crack Opening Displacement (CROD)

Crack Propagation¶

Setting	Description
Convergence Profile	Balance between accuracy and speed (1–5)

Convergence profiles:

Ultra-Precise — highest accuracy, most stable — for validation and publication
Precise & Stable — high accuracy, strong stability — for difficult cases with oscillations
Moderate — recommended default for production
Loose & Fast — lower accuracy — for preliminary studies
Very Loose — fastest — for quick feasibility checks

Attachment Line Residual Strength¶

Setting	Description
Reference Points Per Side	Number of attachment points each side of the crack for residual strength calculation. Swift's recommendation: 15. Range: 10–20. Total reference count is 2x this value.

Fasteners Flexibility¶

Setting	Description
Flexibility Formula	Empirical formula for fastener flexibility: Huth, Grumman, Douglas, or Direct

Discretization Parameters¶

Internal Points¶

Setting	Description
Generate Internal Points	Automatically generate a grid of points inside the boundary for stress calculation
Adaptive Grid	Use concentric layers following boundary shape instead of regular grid
Density Multiplier	Controls spacing of internal points — higher values create denser grid (0.5–1.5)

Patches¶

Setting	Description
Loose Segment Reduction Factor	Size of patch loose segments relative to boundary loose segments — smaller values create denser mesh (0.1–1.5)
Adaptive Grid	Use concentric layers following patch boundary shape
Internal Points Multiplier	Controls spacing of patch internal attachment points (0.1–1.5)

Boundary Elements¶

Setting	Description
Loose Boundary Multiplier	Element size on non-crack boundaries — higher values create larger elements (0.1–10.0)

Crack Elements¶

Setting	Description
Crack Tip Elements	Number of boundary elements for one half of a crack tip (1–20)
Segment Start Multiplier	Size of the first element adjacent to a crack, as percentage of crack tip element size (0–100%)
Segment End Multiplier	Size of the last element in a segment, as percentage of start element size — creates a graded mesh (0–100%)

Style Parameters¶

Application¶

Setting	Description
Font Size	Application-wide font size (8–16)
Toolbar Button Size	Size of toolbar icon buttons (10–32)

Charts¶

Setting	Description
Title Font Size	Font size for chart titles (8–16)
Legend Font Size	Font size for chart legends (6–16)
Axis Labels Font Size	Font size for axis titles, e.g., "Stress [MPa]" (6–16)
Tick Labels Font Size	Font size for axis tick values and colorbar labels (6–16)
Heatmap Color Map	Default color map for heatmap visualizations: Viridis, Plasma, Cividis, Magma, Inferno, Blues, Reds, Greens, Oranges, Purples, RdBu, Coolwarm, PiYG

Application Theme¶

Setting	Description
Color Theme	System (Auto), Light (B&W), or Dark (B&W)
Custom Background	Override the theme background with a user-selected color

File Paths Parameters¶

Setting	Description
Design Database File	Path to a custom `.dbs` database file with material properties
User Directory	Default folder for saving and loading case study files

Both settings are optional — when unchecked, the application uses built-in defaults.

Global Parameters¶

Setting	Description
Logging Level	Verbosity of log messages: Debug (most verbose), Info, Warning, Error, Critical (least verbose)
Maximum Dimension	Characteristic length of the model in millimeters, used for scaling and numerical stability. All units must be consistent (mm).

Reset to defaults

Use Application > Reset Settings to restore all settings to their default values.